Graft copolymers of xanthomonas hydrophilic colloid and acrylic monomer

ABSTRACT

GRAFT COPOLYMERS OF A XANTHOMONAS HYDROPHILIC COLLOID WITH AN ACRYLIC MONOMER. METHOD OF MAKING GRAFT COPOLYMERS BY TREATING A XANTHOMONAS HYDROPHILIC COLLOID AND AN ACRULIC MONOMER IN AN AQUEOUS MEDIUM IN THE PRESENCE OF A CERIC SALT WHICH IS SOLUBLE IN THE ACID CORRESPONDING TO THE ACID ANION IN THE CERIC SALT. THE CERIC SALT IS ADDED IN THE FORM OF A SOLUTION IN THE ACID CORRESPONDING TO THE ACID ANION OF THE SALT AND THE COPOLYMERIZATION IS CARRIED OUT UNDER A PROTECTIVE ATMOSPHERE TO EXCLUDE OXYGEN. THE COPOLYMERIZATION MAY BE CARRIED OUT IN A FERMENTATION BEER CONTAINING A XANTHOMONAS HYDROPHILIC COLLOID AS PRODUCED BY THE GROWTH OF XANTHOMONAS BACTERIA IN THE FERMENTATION MEDIUM.

United States Patent 3,708,446 GRAFT COPOLYMERS 0F XANTHOMONASHYDROPHILIC COLLOID AND ACRYLIC MONOMER David J. Pettitt, San Diego,Calif., assignor to Kelco Company, San Diego, Calif. No Drawing. FiledMar. 24, 1971, Ser. No. 127,796 Int. Cl. C081? 29/50 U.S. Cl. 26017.4 GC37 Claims ABSTRACT OF THE DISCLOSURE Graft copolymers of a Xanthomonashydrophilic colloid with an acrylic monomer. Method of making graftcopolymers by treating-a Xanthomonas hydrophilic colloid and an acrylicmonomer in an aqueous'medium in the presence of a ceric salt which issoluble in the acid corresponding to the acid anion in the ceric salt.The ceric salt is added in the form of a solution in the acidcorresponding to the acid anion-of-the salt and the copolymerization iscarried out under a protective atmosphere to exclude. oxygen. Thecopolymerization may be carried out in a fermentation beer containing aXanthomonas hydrophilic colloid as produced by the growth of Xanthomonasbacteria in the fermentation medium.

The present invention pertains to graft copolymers of a Xanthomonashydrophilic colloid with an acrylic monomer and to a method for theirpreparation. Specifically, the invention pertains to graft copolymers ofa Xanlhm monas campestris colloid with acrylamide and a method for theirpreparation.

Xanthomonas hydrophilic colloids are known materials. Both the colloidsand their method-of preparation are described in a number of UnitedStates patents, e.g.:

United States Nos: 3,232,929, 3,355,447, 3,391,060, 3,-

As described in these prior patents, a Xanthomonas hydrophilic colloidis produced by the fermentation of a carbohydrate with a bacteria of thegenus Xanthomonas. The fermentation medium, as stated, contains acarbohydrate, a nitrogen source, a source of magnesium ions, phosphorus,and water. During the course of the fermentation, the medium is aeratedand the pH of the medium is maintained at about 6.5 to about 7.5.

The Xanthomonas hydrophilic colloid which is obtained from thefermentation is a colloidal polysaccharide polymer. By way ofillustration, the Xanthomonas campestris colloid is a polymer containingmannose, glucose,

potassium glucuronate and acetyl radicals. Various Xan:

thomonas hydrophilic colloids may be produced according to the generalprocedure described above. These colloids may be identified by referenceto the Xanthomonas bacteria utilized in the preparation. Thus,- typical'Xanthomonas colloids include Xanthomona's campestris, Xanthomonascarotae, Xanthomonas incanae, Xanthomonas begoniae and Xanthomonasmalvacearum hydrophilic colloid.

In the preparation of a graft copolymer of a Xanthomonas colloid inaccord with the present invention, the Xanthomonas colloid iscopolymerized with an acrylic monomer. The acrylic monomer may bedefined in terms of the following generic formula:

in which R is either hydrogen or a methyl group and R is -o'n, -NH2 Oron 7 Patented Jan. 2, 1973 alk(C C )OH In addition, R can have thestructure In the above formulas, the symbol alk indicates an alkyl groupfollowed by a representation of the number of carbon atoms in the groupdenoted in parenthesis.

In performing the graft copolymerization reaction, both the Xanthomonascolloid and the acrylic monomer are present in an aqueous medium whichcan be the fermentation beer resulting from the preparation of theXanthomonas colloid. The concentration of the Xanthomonas colloidgenerally ranges between about 1.0 and about 3.0% by weight of the waterin the aqueous medium and it preferably ranges from about 2.0 to about2.5% by weight of the water. The concentration of the acrylic monomermay range from as low as 0.5% to as high as 20% by weight of the water.Preferably, the concentration of the monomer is in the range of about2.0 to about 10.0% by weight and more preferably from about 3 to about6% by weight of the water in the aqueous medium.

Before addition of the ceric catalyst to the aqueous reaction medium,the medium is first purged with an inert gas such as nitrogen, argon,krypton, helium or the like to remove oxygen. If desired, the reactionsystem can first be evacuated prior to introduction of the inert gas or,conversely, the inert gas can be swept over the reaction medium to purgethe system of oxygen. Following the removal of oxygen from the reactionsystem, the ceric catalyst is added. The ceric catalyst can be any cericsalt which is soluble in the acid corresponding to the acid anionpresent in the salt. Thus, for example, the ceric catalyst may be cericnitrate, ceric sulfate, ceric chloride, or ceric perchlorate. The cericsalt is dissolved in the acid corresponding to the acid anion in thesalt prior to its addition to the reaction medium. Thus, the cericnitrate or ceric ammonium nitrate salt would be first dissolved innitric acid; the ceric sulfate salt would be dissolved in sulfuric acid;the ceric chloride salt would be dissolved in hydrochloric acid, and theeerie perchloride salt would be dissolved in perchloric acid. The cericsalt is present in the reaction medium at a concentration which iseffective to cause copolymerization of the Xanthomonas colloid with theacrylic monomer. By Way of example, the concentration of the ceric saltin the reaction medium may range from about 0.05% to about 0.5% byweight and preferably from about 0.11 to about 0.33% by weight.

The pHof the reaction medium is controlled within the range from about 2to about 5 by the addition of nitric, hydrochloric, sulfuric, orperchloric acid as outlined pre viously. The particular acid employedcorresponds to the acidic anion present in the ceric salt. The weightratio of the Xanthomonas colloid to the acrylic monomer used in thecopolymerization reaction may be varied depending upon the propertiesdesired in the graft copolymer product. In general, I have found thatthe weight ratio of Xanthomonas colloid to acrylic monomer can rangefrom about 1:1 to about 1:10.

The copolymerization reaction may be conducted at a reaction temperatureranging from about 0 to about 60 C.,and preferably about 20 to about 30C. The reaction is generally initiated at about room temperature. Thetime required for the reaction may vary but is generally in the order ofabout two to about three hours. During the course of the reaction, thereaction medium becomes more viscous. Thus, the consistency of thereaction medium may be used as a criteria for determining the degree ofcompletion of the reaction. When the reaction is completed, the pH isadjusted to about 58 and preferably about 7 by the addition of asuitable base such as sodium hydroxide, sodium bicarbonate, sodiumcarbonate, a sodium phosphate, the corresponding potassium salt of anyof the foregoing, or ammonia. Also, if desired, a free radical inhibitorsuch as p-methoxyphenol, N,N-di-sec-butyl-p-phenylenediamine, butylatedhydroxytoluene, butylated hydroxyanisole or sodium bisulfite may beadded.

Following this, the product may be separated from the reaction medium byprecipitation through addition of a lower alcohol or ketone, and thendried in any suitable manner, such as by gentle heating.

To further illustrate my invention, there are presented the followingexamples in which all parts and percentages are by weight, unlessotherwise indicated.

EXAMPLE I To a 1000 milliliter reaction vessel equipped with a nitrogeninlet tube, a thermometer, and an addition funnel, was added 500milliliters of a fermentation beer and 10 grams of acrylamide dissolvedin 50 milliliters of water. The fermentation beer contained 2.34 weightpercent of Xanlhomonas campestris colloid, as determined byprecipitation of colloid from a sample of the fermentation beer by theaddition thereto of isopropyl alcohol. The reaction mixture was thenheated to 75 C. while, at the same time, purging the reaction vesselwith nitrogen gas for one hour. Thereafter, the reaction vessel wascooled to room temperature and 20 milliliters of a catalyst solutiondiluted with 50 milliliters of water was added over a period of minuteswhile stirring. The catalyst solution was composed of 0.1 normal cericammonium nitrate dissolved in 1 normal nitric acid. This solution wasmade by dissolving 54.8 g. of ceric ammonium nitrate in l N nitric acidand diluting to make 1 liter of solution. Following the addition of thecatalyst, stirring of the reaction mixture was continued for two hoursat a reaction temperature of to C. after which two grams ofp-methoxyphenol dissolved in 50 milliliters of isopropyl alcohol wasadded. The product was precipitated by the addition of excess isopropylalcohol and was then collected and dried at 45-50 C. for two hours.There was obtained 20.1 grams of product which had a viscosity at aconcentration of 1% by weight in distilled water of 508 centipoises(cps.). By way of comparison, Xanthomonas campestris colloid which wasobtained directly from the fermentation beer had a viscosity at aconcentration of 1% by weight in distilled water of 840 cps.

When Example I is repeated using methacrylamide, N-methyl acrylamide, orN[2-(2-methyl-4-oxopentyl)]- acrylamide, also called diacetoneacrylamide, the X anthomonas campestris-acrylate graft copolymer isobtained in good yield. Similarly, when ceric sulfate in sulfuric acid,ceric chloride in hydrochloric acid, or ceric perchlorate in perchloricacid is used as the polymerization catalyst in Example I, there isobtained the desired X anthomonas campestris-acrylate graft copolymer.

EXAMPLE II The reaction described in Example I was repeated with theexception that the quantity of the acrylamide reactant was 20 grams. Theyield of the Xanthomonas campestrispolyacrylamide graft copolymer was34.2 grams and the product had a viscosity of 187 cps. at aconcentration of 1% by weight in distilled water.

EXAMPLE In The procedure described in Example I was repeated using gramsof acrylamide as a reactant. There was obtained 45.0 grams of the graftcopolymer product which had a viscosity of 112 cps. at a concentrationof 1% by weight in distilled water.

EXAMPLE IV The reaction described in Example I was repeated using 20grams of acrylamide as a reactant. After addition of the catalystsolution, the reaction mixture was stirred for three hours at atemperature of 20 to 25 C. Following this, 1 gram of sodium bisulfiteand 1 gram of sodium bicarbonate were added to the reaction mixture.After precipitation of the product by the addition of excess isopropylalcohol followed by drying, as in Example I, the yield of product was39.0 grams and the product had a viscosity of 342 cps. at aconcentration of 1% by weight in distilled water.

EXAMPLE V To 500 milliliters of a fermentation beer contained in areaction vessel, as described in Example I, was added 25 grams ofacrylic acid in 75 milliliters of distilled water. The mixture washeated to 75 C. for one hour under a nitrogen atmosphere and then cooledto 25 C. under nitrogen. Following this, 20 milliliters of the catalystsolution described in Example I in admixture with 30 milliliters ofdistilled water was added over a period of 15 minutes with stirring.Stirring of the reaction mixture was then continued for two hours undernitrogen after which 2 grams of p-methoxyphenol in 25 milliliters ofisopropyl alcohol was added. After precipitation of the product by theaddition of excess isopropyl alcohol followed by drying, the yield ofthe product was 24.9 grams. The product had a viscosity of 308 cps. at aconcentration of 1% by weight in distilled water after adjusting the pHof the solution to 7 by the addition of sodium bicarbonate. Theconcentration of the Xanthomonas campestris colloid in the fermentationbeer employed in the reaction was 2.16% by weight, as determined in themanner described in Example I.

When Example V is repeated using methacrylic acid as the acrylicmonomer, the Xanthomonas campestris acrylate graft copolymer isobtained. Also, the use of Xanthomonas colloids other than theXanthomonascampestris colloid in Example V produces the Xanthomonascolloidacrylate graft copolymere.g., Xanthomonas carolateacrylatecopolymer, Xanthomonas begoniae-acrylate copolymer, Xanthomonasincanae-acrylate copolymer and Xanthomonas malvacearum-acrylate graftcopolymer.

EXAMPLE VI 50 grams of acrylamide and 12.5 grams of acrylic acid wereadded to 500 milliliters of a fermentation beer containing 2.0% byweight of Xanthomonas campestris colloid. After heating the mixture to75 C. for one hour followed by cooling to 25 C. (all under a nitrogenatmosphere in a reaction vessel as described in Example I) there wereadded 20 milliliters of the catalyst solution prepared as in Example I,diluted with 25 milliliters of distilled water. The addition was madeover a period of 15 minutes with stirring. After addition of thecatalyst solution, the mixture was stirred for three hours after which17 grams of sodium bicarbonate in milliliters of water was added. Theproduct was then precipitated by the addition of excess isopropylalcohol and the product was then dried for three hours at a temperatureof about 45 to 50 C. The product had a viscosity of 548 cps. at aconcentration of 1% by weight in distilled water and the yield of theproduct was 97.6 grams.

EXAMPLE VII To a reaction vessel, as described in Example I, containing500 milliliters of a fermentation beer there was added 20 grams ofacrylamide and 10 grams of diacetone acrylamide in 250 milliliters ofwater. The fermentation beer contained 1.2% by weight of Xanthomonascamp estris colloid, as determined in the manner described in Example I.The reaction mixture was then purged with nitrogen at a temperature of25 C. for 1 /2 hours and milliliters of catalyst solution in 25milliliters of water was added over a period of minutes with stirring.The catalyst solution employed was the same as that described in ExampleI. After stirring the reaction mixture for 2 /2 hours at a reactiontemperature of to C. under nitrogen, 1 gram of sodium bicarbonate wasadded. The product was then precipitated by the addition of isopropylalcohol and dried. The yield of the product was 36.0 grams and theproduct had a viscosity of 183 centipoises at a concentration of 1% byweight in distilled water.

EXAMPLE VIII ,The procedure described in Example VII was repeated usingas the acrylic monomer a mixture of 10 grams of acrylamide and 10 gramsof diacetone acrylamide, The yield of the product was 18.7 grams and theproduct had a viscosity of 319' cps. at a concentration of 1% by weightin distilled water.

The fermentation beer, containing the Xanthomonas colloid, which may beused as the reaction medium for my copolymerization reaction, is acomplex mixture containing various inorganic salts such as ammonium oralkali metal phosphates and nitrates and alkaline earth phosphates,nitrates or sulfates. Organic components may include protein which maybe present as enzymes such as cellulase. A variety of organic acids andtheir salts may be present and also some sugars may be present.Typically, such a fermentation beer contains an alkali metal phosphate,ammonium nitrate, magnesium sulfate, cellulase and other enzymesproduced by the bacteria, a small amount of residual sugar and somesalts of organic acids produced as by-products of the bacterialfermentation.

My graft copolymerization reaction may, of course, also be carried outin water. However, it is most conveniently carried out in a fermentationbeer containing the Xanthomonas colloid since this eliminates the stepof separating the Xanthomonas colloid from the beer prior to its use asa reactant in my process. In view of the complexity of the fermentationbeer in terms of its chemical composition, it is quite surprising thatthe copolymerization reaction can be carried out. in the beer, The factthat the reaction can be carried out in the beer represents asubstantial advantage.

The properties of my graft copolymers are highly ad vantangeous in thatthe copolymers retain many of the desirable characteristics of theXanthomonas colloids while, at the same time, having properties whichare altered from those of the colloid. Like the Xanthomonas colloids, mygraft copolymers provide aqueous viscosities which are highlypseudoplastic; i.e., their viscosities vary inversely with respect toshear. As the shear force applied to an aqueous medium containing thegraft copolymer is increased, the viscosity of the medium is immediatelydecreased. Conversely, as the shear applied to the aqueous medium isdecreased, the viscosity of the aqueous medium is immediately increased.The property of pseudoplasticity is highly advantageous, for example, inan aqueous drilling mud since it provides the mud with a high viscositywhen at rest, or near rest, such that it can suspend cuttings andweighting agents within the mud. Yet, at the same time, such a drillingmud is easily pumped and provides satisfactory lubrication of the drillbit since its viscosity immediately drops when it is subjected to shearforces in a pump or at the bit. Thus, may graft copolymers may beemployed as additives to aqueous drilling fluids to providepseudoplastic viscosity characteristics in the fluids.

The aqueous viscosities of my graft copolymers are lower than theviscosities of the Xanthomonas colloids used in their preparation andthe viscosity of the copolymer is determined by. the weight ratio of theacrylate to the Xanthomonas colloid in the copolymer. As the weightratio of the acrylate to Xanthomonas colloid in the copolymer isincreased, the aqueous viscosity of the copolymer is reduced. Thus, forexample, the viscosity of Xanthomonas campestris hydrophilic colloid ata concentration of 1% by weight in aqueous media is about 1000 cps.while the 1% aqueous viscosities of Xanthomonascampestris-polyacrylamide graft copolymers are about 500 cps., about 300cps., and about cps. at weight ratios of polyacrylamide to Xanthomonascolloid of 1:1, 2:1, and 3:1, respectively. By adjusting the acrylate toXanthomonas colloid weight ratio in my graft copolymers, I am able toprovide products having a wide range of viscosities.

My graft copolymers are quite stable in aqueous media to changes in pH.Between a pH of 2 and a pH of 12, their viscosities are virtuallyunaffected while at a pH of 1 or a pH of 13 there was a drop inviscosity of about 20 percent. Also, my graft copolymers were found tobe relatively unreactive with salts, namely, sodium sulfate, calciumchloride and chromium chloride. The addition of these salts in 0.5 gramincrements to a 2% by weight aqueous solution of a graft copolymerhaving a 2:1 weight ratio of polyacrylamide to X anthomonas campestrz'scolloid caused only a slight viscosity increase.

The presence of locust bean gum with my graft copolymers in aqueousmedia was found to cause greatly increased thickening or the formationof a gel. Thus, my invention includes compositions which are mixtures oflocust bean gum with my graft copolymers in which the locust bean gum ispresent in an amount sufficient to cause a synergistic thickening whenthe mixture is added to an aqueous medium. By Way of example, the locustbean gum may be present in an amount sufficient to produce a viscosityincrease in the aqueous medium of about 20 cps. or more than theadditive effect of the viscosities produced by the individual componentsin the aqueous medium. By way of example, such mixtures may have aweight ratio of locust bean gum to graft copolymer ranging from about0.121 to about 10:1. These ratios are merely illustrative since thelocust bean gum can be present in any amount which is effective toincrease the viscosity of my graft copolymer or to form a gel with itwhen copresent in an aqueous medium.

The concentration of my graft copolymers, when present in an aqueousmedium to produce thickening, can range from about 0.1 to about 10% byweight of the water in the medium.

The above described properties of my graft copolymers make themadmirably suited for use as textile print paste thickeners.

I claim:

1. A process for preparation of a Xanthomonas colloid-polyacrylic graftcopolymer, said process comprising reacting a Xanthomonas colloid withan acrylic monomer in an aqueous medium, said reaction being carried outunder conditions to exclude oxygen and in the presence of a ceric saltcatalyst at a concentration which is effective to cause copolymcrizationof said Xanthomonas colloid with said acrylic monomer, maintaining thepH of the reaction medium at about 2 to about 5 by the addition of anacid corresponding to the acidic anion present in said ceric salt, saidreaction being carried out at a reaction temperature from about 0 toabout 60 C., with said acrylic monomer having the formula:

in which R is either hydrogen or a methyl group, R is --OH, -NH OR", or

and R" is an alkyl group containing from 1 to about 10 carbon atoms or ahydroxyalkyl group containing from 1 to about 10 carbon atoms, whereinthe concentration of Xanthomonas colloid in the reaction medium rangesfrom about 1 to about 3% by weight of the water and the concentration ofacrylic monomer in the reaction medium ranges from about 0.5% to about20% by weight of the water.

2. The process of claim 1 wherein the reaction is carried out in thepresence of an inert gas.

3. The process of claim 1 wherein said Xanthomonas colloid is a Xanthomonas campestris colloid.

4. The process of said claim 1 wherein said ceric salt catalyst is cericnitrate, ceric sulfate, ceric chloride, or ceric perchlorate.

5-. The process of claim 1 wherein the concentration of said ceric saltin the reaction medium ranges from about 0.05% to about 0.5% by Weight.

6. The process of claim 1 wherein the reaction is conducted at atemperature of about 20 to about 30 C.

7. The process of claim 1 wherein a free radical inhibitor is present inthe reaction medium.

8. The process of claim 1 wherein said acrylic monomer is acrylamide,methacrylamide, N-methyl acrylamide, acrylic acid or mixtures thereof.

9. The process of claim 3 wherein said acrylic monomer is acrylamide,methacrylamide, N-methyl acrylamide, acrylic acid or mixtures thereof.

10. The process of claim 1 wherein the acrylic monomer is acrylamide.

11. The process of claim 3 wherein the acrylic monomer is acrylamide.

12. The process of claim 1 wherein the concentration of said acrylicmonomer is about 2 to about 10% by weight of the water in said aqueousmedium.

13. The process of claim 1 wherein the concentration of said acrylicmonomer is about 3 to about 6% by Weight of the water in said aqueousmedium.

14. The process of claim 1 wherein said aqueous medium is a fermentationbeer containing the Xanthomonas colloid.

15. The process of claim 3 wherein said aqueous medium is a fermentationbeer containing the Xanthomonas campestris colloid.

16. A Xanthomonas colloid-polyacrylic graft copolymer wherein the Weightratio of Xanthomonas colloid to acrylic monomer ranges from about 1:1 toabout 1:10 prepared according to the process of claim 1.

17. The graft copolymers of claim 16, wherein said Xanthomonas colloidis a Xanthomonas campeszris colloid.

18. The graft copolymers of claim 16 wherein the acrylic monomer isacrylamide, methacrylamide, N- methyl acrylamide, acrylic acid ormixtures thereof.

19. The graft copolymers of claim 16, wherein said acrylic monomer isacrylamide.

2.0. The graft copolymers of claim 17, wherein said acrylic monomer isacrylamide.

21. The graft copolymers of claim 16, wherein the weight ratio ofXanthomonas colloid to acrylic monomer is about 1:1 to about 1:3.

22. An aqueous medium containing a Xanthomonas colloid-polyacrylic graftcopolymer as defined in claim 1 wherein the concentration of said graftcopolymer in said aqueous medium ranges from about 0.1% to about 10% byweight of the water present therein.

23. The composition of claim 22 wherein the Xanthomonas colloid presentin said graft copolymer is a X anthomonas campestris colloid.

24. The composition of claim 22 wherein the acrylic monomer present insaid graft copolymer is acrylamide, methacrylamide, N-methylacrylamide,acrylic acid, or mixtures thereof.

25. The composition of claim 22 wherein the acrylic monomer present insaid graft copolymer is acrylamide.

26. The composition of claim 23 wherein the acrylic monomer present insaid graft copolymer is acrylamide.

27. A composition comprising locust bean gum in admixture with aXanthomonas colloid-polyacrylic graft copolymer wherein the weight ratioof Xanthomonas colloid to acrylic monomer ranges from about 1:1 to about1:10, said copolymer having been prepared according to claim 1.

28. The composition of claim 27 wherein said Xanthomonas colloid is aXanthomonas campestris colloid.

29. Edge composition of claim 27 wherein said acrylic monomer isacrylamide.

30. The composition of claim 28 wherein said acrylic monomer isacrylamide.

31. The composition of claim 27 wherein the weight ratio of locust beangum to said graft copolymer ranges from about 0.1:1 to about 10:1.

32.. An aqueous medium containing the composition defined in claim 27 inan amount suflicient to increase the viscosity of said medium.

33. The composition of claim 32 wherein said Xanthomonas colloid is aXanthomonas campestris colloid.

34. The composition of claim 32 wherein said acrylic monomer isacrylamide.

35. The composition of claim 33 wherein said acrylic monomer isacrylamide.

36. The composition of claim 32 wherein the weight ratio of locust beangum to said graft copolymer ranges from about 0.1:1 to about 10:1.

37. The composition of claim 32 wherein said graft copolymer is presentin an amount ranging from about 0.1 to about 10% by weight of the waterpresent therein.

References Cited Chem. Abstr., vol. 67: 75061n, Deily et al., NewBiopolymer Drilling Operation.

Chem. Abstr., vol. 69': 54581h, Kelco Co., Heat Reversible Gel.

WILLIAM H. SHORT, Primary Examiner E. WOODBERRY, Assistant Examiner

